A challenge confronting the development and distribution of advanced high energy battery technology is the stability and safety of the electrolyte system. In currently manufactured advanced batteries, the electrolyte is usually comprised of aprotic organic liquids such as, for example, dimethyl carbonate, ethylene carbonate, and propylene carbonate. A problem with such electrolyte materials, beyond the well-known solid-electrolyte interface (SEI) issues, is volatility and flammability. An electrical short between the cathode and the anode generally results in a large amount of energy being released spontaneously. Such an energy release often leads to catastrophic combustion of the organic electrolyte and a fire. Such fires have resulted in expensive consumer recall, loss of consumer confidence, and the destruction of a nascent battery industry.
U.S. Pat. No. 9,590,274, “Impact Resistant Electrolytes” discloses an electrolyte that is passively impact resistant to address these issues. The disclosure of this reference is incorporated fully by reference. A passively impact resistant composite electrolyte composition undergoes a passive shear thickening phenomenon upon application of an external force, introducing a significant passive resistance against mechanical damage. Integration of a passive shear thickening effect and enhanced transport of a specific silica material into a liquid electrolyte provides greatly improved stability and safety.
Fabrication of electrodes for energy storage devices with such shear thickening electrolytes presents some challenges. Typically, battery electrodes based on a slurry formulation utilize fabrication techniques, such as slot die coating or tape casting that moves the slurry across a support surface. The slurry is moved by shearing the material across the current collector surface. If the electrode formulation mixture is a shear thickening composition it will not flow as required to make a thin, uniform coating.
Normal battery electrolytes are liquids and injected into a dry, pre-assembled, cell where the electrolyte wets and fills the cell and separator structure. This process will not work for a shear thickening electrolyte because the force of injection will turn it solid and it will not flow and there will be no pore filling. Second, the solvent part of the shear thickening electrolyte will be selectively wicked into the cell and the ceramic particles will not be distributed in the cell homogenously. This also causes an increase in solution viscosity acerbating the thickening issue. This homogeneousness is critical for impact and thermal safety.